1. Field of the Invention
The present invention relates to a liquid fuel feeding method and to a liquid fuel burning apparatus, and more particularly, to a method of feeding liquid fuel to a warm air circulator, and to a warm air circulator employing said method.
2. Description of the Prior Art
As shown in FIG. 18, in a conventional liquid fuel burning apparatus of the kind referred to above, an electromagnetic pump 602 is provided above a tank 601 which contains liquid fuel. The electromagnetic pump 602 sucks the liquid fuel from the tank 601 and feeds the sucked fuel to a burning unit 604 through an fuel feed pipe 603.
In FIG. 19, an evaporating unit 604 which is located inside the burning unit 604 is shown. The evaporating unit 604 is heated to high temperature by a heater 605 so that the fuel supplied from a nozzle 607 provided at an end of the fuel feed pipe is evaporated and mixed with the burning air fed through an air throat 608. The mixture of evaporated fuel and air is jetted out from a flame opening 609 of the evaporating unit 606 for burning.
Meanwhile, as shown in FIG. 20, the electromagnetic pump 602 drives a discharge valve 611 and a suction valve 612 in accordance with the up-and-down movement of a plunger 610, thereby sucking the fuel from the tank 601 for feeding to the burning unit 604 through the fuel feed pipe 603.
In the above-described structure, however, the liquid fuel which is not used and remaining inside the fuel feed pipe 603 within the burning unit 604 is expanded as a result of the temperature rise of the fuel feed pipe or nozzle 607 facing to the inside of the evaporating unit 606 of the burning unit 604. Thus, thermally expanded fuel in the fuel feed pipe 603 is fed to the burning unit 604 through the nozzle and the evaporating unit 606 even when the electromagnetic pump 602 is stopped.
For instance, although the fuel feed pipe 603 in the vicinity of the burning unit 604 and the nozzle 607 face the high temperature ambience during the burning of the fuel, the fuel feed pipe 603 and nozzle 607 are cooled by the liquid fuel sucked up from the tank 601 by the pump 602. In contrast, when burning is stopped, supply of the liquid fuel sucked from the tank 2 is interrupted. The cooling effect on pipe 603 or nozzle 607 by the liquid fuel is lost, whereby the temperature of the liquid fuel in the fuel feed pipe 603 and nozzle 607 raises rapidly, causing feed of the expanded fuel to the burning unit 604 with a little delay from the stop of burning. The expanded fuel in pipe 608 and nozzle 609 is then dropped in the evaporating unit 606 of the burning unit 604, thus generating a large quantity of unburnt gas, horrible smell and tar, etc.
At the ignition time as well, the liquid fuel remaining in the fuel feed pipe 603 and nozzle 607 is expanded due to the temperature rise of the evaporating unit 606 before the ignition, and evaporated in the evaporating unit 606 of the burning unit 604, thus resulting in generation of a large deal of unburnt gas, smell and tar, etc.
The above phenomenon is particularly apparent when the temperature of the fuel feed pipe 603 and nozzle 607 is ready to rise immediately after the electromagnetic pump is stopped. This gives the user greatly uncomfortable feeling.